1. Field of the Invention
The present application relates to an organic light emitting device (OLED) and a use thereof.
2. Discussion of Related Art
A typical OLED sequentially includes a substrate layer, a first electrode, an organic layer including at least an emitting layer and a second electrode.
In a structure called as a so-called bottom emitting device, the first electrode may be a transparent electrode, and the second electrode may be a reflective electrode. Also, in a structure called as a so-called top emitting device, the first electrode may be formed by a reflective electrode and the second electrode may be formed by a transparent electrode.
Electron and hole are injected respectively by the two electrode, and the injected electron and hole are recombined in the emitting layer, resulting in generating light. The light may be emitted to the substrate layer in the bottom emitting device or to the second electrode in the top emitting device.
In the structure of the OLED, indium tin oxide (ITO) generally used as the transparent electrode, the organic layer, and the substrate layer, which is conventionally formed of glass, have refractive indexes of about 2.0, 1.8 and 1.5, respectively. In such a relationship of the refractive index, for example, the light generated in the organic emitting layer in the bottom emitting device is trapped by total internal reflection phenomenon between the organic layer and the interface of the first electrode or in the substrate and a very small amount of light is only emitted.